Current state of the art scraping apparatus of the aforementioned type are already known, among which examples can be cited such as the documents of Patent EP1746206, EP1734182, EP1381733, EP1042554 and WO2006091427.
The known solutions present limitations and/or defects; in them, when the extraction is carried out laterally and with no movement in another direction, there is no reliable system which allows the elimination of clearances in the zones which are far from the sides of the doctor.
Because of this, the clearances in the guide cannot be elevated and consequently:
a1) the operations of insertion and extraction of the blade support may have their difficulties.
a2) as the guide becomes dirtier, the operation of insertion and extraction becomes more difficult to realize (and if the initial clearance is not elevated, this problem is accentuated.
b) The positioning of the blade may not be repetitive.
c) When unexpected forces appear in the process, for example, impact due to the passing of a sheet of paper) the system could lose the preload and vibrations could occur due to the clearances.
d) In order to eliminate said clearance, in previous solutions, a mechanical blocking solution was used, installed inside the slot, a mechanical solution which:
d1) may become blocked by dirt, making extraction of the blade support difficult or impossible.
d2) uses a spline which undergoes significant deformations in each extraction and insertion operation, and could therefore have fatigue problems.
To solve these limitations and/or defects, known technology utilizes:                elevated clearances        anchoring in different longitudinal positions of the blade support to avoid the problems caused by elevated clearances.        fastening systems whose functionality is not affected by dirt.        
The scraping apparatus of the present invention provides a solution to these limitations and/or defects with unique technology which uses magnetic forces to anchor the blade support to the frame. The use of magnetic forces allows the fixing force to be deactivated or activated with a simple operation. Moreover, said operation of activation or deactivation can be carried out at a distance. Thus, from the side of the doctor, the force produced along the entire length of the doctor can be activated or deactivated.
The magnetic anchor makes it possible for the system to use elevated clearances in the guidance system, which results in greater ease of extraction and insertion, as once the system is set up, we eliminate said clearance with magnetic forces. Moreover, in certain specific embodiments, a system can be made whose positioning is repetitive.